Shield attached by sealing to panel sidewall of cathode ray tube

ABSTRACT

Improved electron dispersion shielding means are provided to prevent over-scan electron beams from penetrating the spacing between the mask member and the panel sidewall in a color cathode ray tube. The expansive spanning portion of the shield, which bridges the spacing, has configurated projecting means extended from the leading edge thereof. The projection means are oriented for partial transversal embedment in the perimetrical seal, joining the viewing panel and funnel portions of the tube envelope; and thereby provide a beneficial ruggedizing feature for the mask of the tube which insures positive peripheral shielding therearound.

United States Patent 1 Shinal 1 1 Mar. 25, 1975 SHIELD ATTACHED BY SEALI NG TO PANEL SIDEWALL OF CATHODE RAY TUBE Inventor: Joseph B. Shinal, Seneca Falls, NY.

GTE Sylvania Incorporated, Stamford, Conn.

Filed: Feb. 20, 1974 Appl. No.: 443,978

Assignee:

US. Cl. 313/402, 313/407 1m. C1. HOlj 29/06, H01 j 31/20 Field of Search 313/402 407, 408

References Cited UNITED STATES PATENTS Fyler 313/402 X Woughter'et al. 313/402 Godfrey 313/408 Fiore 313/451 X Mears 313/402 3,541,373 11/1970 Barr ..313/407 Primary ExaminerRobert Segal Attorney, Agent, or Firm-Norman J. OMalley; Frederick H. Rinn; Cyril A. Krenzer [5 7] ABSTRACT Improved electron dispersion shielding means ar provided to prevent over-scan electron beams from penetrating the spacing between the mask member and the panel sidewall in a color cathode ray tube. The expansive spanning portion of the shield, which bridges the spacing, has configurated projecting means extended from the leading edge thereof. The projection means are oriented for partial transversal embedment in the perimetrical seal, joining the viewing panel and funnel portions of the tube envelope; and thereby provide 21 beneficial ruggedizing feature for the mask of the tube which insures positive peripheral shielding therearound.

3 Claims, 4 Drawing Figures SHIELD ATTACHED BY SEALING TO PANEL SIDEWALL OF CATHODE RAY TUBE BACKGROUND OF THE INVENTION This invention relates to color cathode ray tubes and more particularly to electron dispersion shielding means peripherally associated with the mask member in a color tube.

Color cathode ray tubes conventionally employ a plurality of internally emitted electron beams which are directed in a manner to traverse a foraminous mask member and selectively impinge a spacedly related cathodoluminescent pattern screen disposed on the viewing panel of the tube therebeyond. The foraminous mask member is usually positioned within the panel portion by support means extended from the sidewall thereof.

During the usual procedure utilized in forming the patterned screen on the viewing panel, it is necessary to remove and precisely reinsert the mask member therein several times in accordance with the manufacturing stages of the process. Such removal and replacement of the mask member is readily facilitated by hav-- ing the mask member dimensioned perimetrically smaller than the internal dimensions of the panel thereby effecting a peripheral spacing therearound. To prevent electron beam leakage or overscan from reaching the patterned screen through this peripheral spacing, a protective structure or beam shielding means is conventionally attached to the mask member. This electron dispersion shield is so shaped to effectively bridge the space between the shadow mask and the adjacent panel sidewall. This peripheral shielding is oriented and securely attached to the mask member after the patterned screen has been completely formed and the associated mask member has been finally positioned within the viewing panel. Since the shielding member is usually formed of very thin metallic material, such as aluminum for example, it is prone to bend or permanently deform if the tube is accidentally subjected to a severe mechanical shock of sufficient degree to cause the mask member to momentarily shift in position. Such deformation of the shielding member often effects an opening or gap between the mask member and the panel sidewall through which deleterious electron leakage may penetrate to the region of the screen. It has also been found that the temperatures encountered during tube processing sometimes cause the shielding means to slightly deform thereby providing inadequate peripheral shielding. At this stage in cathode ray tube manufacturing, there is no procedure for correcting defective shielding within the tube. During usage, there are occasions when the color cathode ray tube may be operated in an environment where vibratory influences are apt to be present. For example, a momentary impact or repetitive vibration on a television receiver, whereof the cabinetry often responds as an echo chamber, may cause the beam shielding means and the associated mask to vibrate thereby producing transient waves which are noticeably visible in the imagery displayed on the cathode ray tube screen. If the impact is of sufficient severity, the beam shield may be permanently deformed in a manner to allow passage of electron leakage thereby impairing the color purity of the cathode ray tube display.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to reduce the aforementioned disadvantages by providing an improvement in the electron dispersion shielding means.

It is another object of the invention to provide an improved electron dispersion shielding means that incorporates a ruggedizing feature therein.

It is a further object of the invention to provide an improved and more rugged color cathode ray tube wherein the positioning of the electron dispersion shielding means remains substantially secure.

These and other objects and advantages are achieved in one aspect of the invention wherein the electron dispersion shielding means has a seating portion formed for attachment to the apertured mask member, and whereof the shielding means has an expansive spanning portion shaped to extend peripherally around the mask member in a substantially continuous manner to bridge the peripheral spacing existent between the mask member and the panel sidewall. Integral with the expansive spanning portion, and extending from the leading edge thereof, are discretely configurated projecting means which are oriented for partial transversal embedment in the perimetrical seal joining the viewing panel and funnel portions of the tube envelope.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a diagrammatic section of a color cathode ray tube illustrating the invention;

FIG. 2 is a partial sectional perspective view showing the orientation of the invention;

FIG. 3 is an enlarged cross-sectional view illustrating another embodiment of the improvedelectron dispersion shielding means in association with related tube structure; and

FIG. 4 is an enlarged partial perspective of the improved shielding means particularly depicting one embodiment ofthe configurated projecting means thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following specification and appended claims in connection with the aforedescribed drawings.

With reference to the drawings, there is shown in FIG. 1 a diagrammatic view of a conventional color cathode ray tube 11 of the type employing a multiapertured mask member 13 which is spatially related to a patterned cathodoluminescent screen 15 disposed upon the interior surface of the tube viewing panel 17. The source for generating electron beams 19 is'positioned within the neck portion 21 of the tube envelope. There is shown an exemplary electron beam 23 which, upon emanation therefrom, is directed toward and through the multi-apertured mask member 13 to impinge the patterned screen 15 therebeyond.

In greater detail, the apertured mask member, which is spacedly positioned within the viewing panel portion 17 of the tube envelope, is suitably supported therein relative to the panel sidewall 25 by means not shown. As illustrated in FIGS. 1 and 2, the mask member 13 comprises a perimetral framing or reinforcing means 27 to which a substantially domed foraminous section 29 is attached. While the multi-apertured mask section is shown to have substantially circular openings therein, such is not limiting as the openings may also be of ovate or elongated shapings in keeping with the associated screen pattern desired. The existent peripheral spacing 31 between the mask member 13 and the sidewall 25 of the viewing panel is bridged by electron dispersion shielding 33 which prevents the overscan and reflected electrons from entering the spacing 31 and spuriously exciting the edge regions of the screen 15. Such shielding is usually formed and installed in several substantially overlapping sections to facilitate installation and subsequent expansion and contraction.

The electron dispersion shielding means of thisinvention have a seating portion 35 which is formed for attachment to a compatibly formed portion 37 of the mask member 13; such attachment being consummated for example by spaced apart bondings such as spot welds 39 or clip means, not shown. Protruding beyond this seating portion 35 and integral therewith is an expansive spanning portion 41 shaped to extend peripherally beyond the mask member in a substantially continuous manner to bridge the aforementioned peripheral spacing 31 between the mask and the adjacent sidewall. The expansive spanning portion 41, as deline-' ated in FIGS. 1 and 2, is substantially a U-shaped channel formation having an inherent degree of resilience to substantially retain the discrete configuration of the shaping upon being subjected to thermally induced expansion and contraction encountered during tube processing and subsequent operation. The shielding means per se are usually fabricated of thin metallic material having a nominal thickness in the order of 3 to mils.

Integral with the expansive spanning portion 41 of the shielding means and extending outward therefrom are configurated projecting means 43. As shown in FIG. 2, these projecting means are shown, for example, as spaced apart fin-like tab portions which are formed for embedment in selected regions of the perimetrical seal 47 joining the face panel 17 and funnel 49 portions of the tube envelope. This type of seal is conventionally formed of a heat bonding material, such as an appropriate glass frit formulation. Factually, the segments of the leading edge 51 of the expansive portion 41, as evidenced between the spaced-apart tab portions 43, are substantially contiguous with the interior edge of the perimetrical seal 47 and the panel sidewall to effect efficient shielding. These fin-like projections 43 protruding beyond the expansive portion extend in a plane A that is substantially parallel to and substantially mating with the plane B of the seating edge 53 of the panel portion 17.

While the surface of the tabs may or may not be sealingly adherent with the sealing substance, it is important that the projecting means 43 per se be formed of a thin material having a coefficient of thermal expansion that substantially matches that of the substance comprising the perimetrical seal 47. As such, these tabportions may be material extensions of an appropriate metallic composition constituting the spanning portion 41, or they may be of a different but suitable material compatibly bonded or brazed thereto. To insure a strong hermetic seal, it is to be noted that these projecting means extend in only a partial transversal manner into the seal, and it is preferred that they be configurated so as to be securely anchored in the seal material. One such configuration of a projecting tab 43' is delineated in FIG. 4, wherein discretely configurated edgeoriented indentations 57, such as of pseudocuneiform shapings, are formed in a manner to define tongue-like appendages 59 for effecting augmented securement in the seal. For example, the natural pressure inherent in the conventionally utilized sealing technique, for joining the panel and funnel portions forceflows the sealing material into and around the indentations thereby effecting positive subsequential securement of the tab portion embedded therein.

-With reference to FIG. 3, there is illustrated another embodiment of the spanning portion 41 of the dispersion shielding means depicting a substantially corrugated-shaping whereof the hills 61 and valleys 63 are substantially longitudinally parallel with the periphery of the mask member. This accordianeffect is another means for accommodating differential expansion and contraction of the mask member 13 with that of the panel portion 17.

The improved electron dispersion shielding means of the invention incorporates a ruggedizing feature that is markedly beneficial in achieving the desired operational results of a color cathode ray tube. The anchoring of the shielding means in the perimetrical seal 47 effects dampening of spurious vibrations, which would tend to cause flutter of the thin foraminous domed portion of the mask member, thereby minimizing visible pattern distortions in the display imagery. Thus, such ruggedizing reduces sensitivity of cathode ray tubes operating in or near vibrating areas. Furthermore, the improved electron dispersion shielding of the invention prohibits slippage of the beam shield during processing, handling, and shipping. Therefore, improved color pu rity of the tube display imagery is achieved by preventing beam shield leakage resulting from improperly installed or slipped shields. The invention insures complete and retentive protective closure of the spacing between the panel sidewall and the related mask member.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.

,What is claimed is:

1. An improvement in a color cathode ray tube having a patterned cathodoluminescent screen disposed on the viewing panel thereof in a manner to receive electrons beamed through a related multi-apertured mask member having perimetrical framing means supported within the panel by means relative to the panel sidewall in spatial relationship to said screen, and whereof the seating edge of the panel is bonded by a sealing substance to the mating edge of the funnel member of the tube envelope to provide a hermetically formed perimetric seal therearound, said improvement being a ruggedizing feature comprising:

electron dispersion shielding means formed of a material lighter than that of said mask framing means and having a seating portion attached to said mask framing means and an expansive spanning portion having at least on hill and valley extending peripherally around said mask member in a substantially continuous manner to bridge the peripheral spacing between said member and said panel sidewall; and

configurated projecting means of a material substantially matching the coefficient of thermal expantend in a plane parallel to and substantially mate with that of the seating edge of said panel.

3. The improvement in said electron dispersion shielding means according to claim 1 wherein said spanning portion is shaped to facilitate expansion and contraction thereof without stressing said perimetrical seal.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 13,873,874 DATED :March 25, 1975 INVENTOR(S) Jose h B. Shinal It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, Line 62: "on hill" should read one bill Signed and sealed this 13th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH c. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. An improvement in a color cathode ray tube having a patterned cathodoluminescent screen disposed on the viewing panel thereof in a manner to receive electrons beamed through a related multiapertured mask member having perimetrical framing means supported within the panel by means relative to the panel sidewall in spatial relationship to said screen, and whereof the seating edge of the panel is bonded by a sealing substance to the mating edge of the funnel member of the tube envelope to provide a hermetically formed perimetric seal therearound, said improvement being a ruggedizing feature comprising: electron dispersion shielding means formed of a material lighter than that of said mask framing means and having a seating portion attached to said mask framing means and an expansive spanning portion having at least on hill and valley extending peripherally around said mask member in a substantially continuous manner to bridge the peripheral spacing between said member and said panel sidewall; and configurated projecting means of a material substantially matching the coefficient of thermal expansion of said sealing substance formed integral to said expansive spanning portion extending from the leading edge thereof as discrete spaced apart fin-like tab portions having edge-oriented indentations formed to effect only partial transversal embedment in selected regions of said perimetrical seal.
 2. The improvement in said color cathode ray tube according to claim 1 wherein said projecting means extend in a plane parallel to and substantially mate with that of the seating edge of said panel.
 3. The improvement in said electron dispersion shielding means according to claim 1 wherein said spanning portion is shaped to facilitate expansion and contraction thereof without stressing said perimetrical seal. 